Method and Device for Producing a Composite Sheet-Metal Part with a Metal Edge Region

ABSTRACT

The invention relates to a method for producing a composite sheet metal part with a metal edge region comprising two outer covering sheets of metal and at least one layer consisting of a plastic arranged between the covering sheets. The method is characterised in that a selected edge region of the composite sheet metal part is heated in such a way that the plastic layer arranged between the outer covering sheets softens, by applying a force to at least one outer covering sheet in the edge region the covering sheets are pressed against one another at some points or regions, so that the plastic layer in the edge region subjected to the force is expelled, and subsequently or at the same time as the application of the force both covering sheets in the compressed edge region are joined to one another at least over some regions or points.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This patent application is a continuation of PCT/EP2012/070041, filed Oct. 10, 2012, which claims priority to German Application No. 102011054362.7, filed Oct. 10, 2011, the entire teachings and disclosure of which are incorporated herein by reference thereto.

FIELD OF THE INVENTION

The invention relates to a method for producing a composite sheet metal part with a metal edge region, which comprises two outer covering sheets of metal and at least one layer consisting of a plastic arranged between the covering sheets. In addition, the invention relates to a device for carrying out the method according to the invention.

BACKGROUND OF THE INVENTION

Composite sheet metal parts are often used in the form of a sandwich sheet, which comprises two outer covering sheets and a non-metallic sheet, normally consisting of a plastic that is arranged between the covering sheets. One reason for the increasing use of composite sheet metal parts is the fact that composite sheet metal parts can have properties that are often mutually excluded in a sheet of solid material. A composite sheet metal part provides for example, despite its low weight, locally extremely good stiffness properties and can at the same time exhibit very good sound-damping properties. Many applications mean, however, that these composite sheet metal parts have to be joined to other sheet metal parts or metal parts. The joining methods commonly used with sheets, such as fusion welding and soldering, cause problems, however, on account of their high energy input. With the high energy input, the composite sheet metal part may be damaged due to the fact that the non-metallic layer or plastic layer arranged between the covering sheets is damaged by the heat input, and as a result a sufficiently good connection between a composite sheet metal part and a metal part can be achieved only with difficulty. Hitherto various approaches have been attempted in order to solve this problem. From Japanese patent application JP 06-087079 A it is known to prepare the edge region, often used for the joining to further parts, of a composite sheet metal part for a weld joint by first of all heating the edge region of the composite sheet metal part, bending the two outer covering sheets over in the edge region, and removing the plastic layer arranged between the covering sheets by employing abrasive means. The covering sheets of the edge region are then welded to one another, so that a composite sheet metal part with a purely metal edge region is made available, which can then be used for conventional joining methods. This method is, however, very complicated and can be automated only with difficulty.

Starting from this prior art the object of the present invention is accordingly to provide a method for producing a composite sheet metal part with a metal edge region that enables a corresponding sheet metal part to be produced economically and with a high degree of automation. In addition, the object of the invention is to propose a device to be used for carrying out the said method.

SUMMARY OF THE INVENTION

According to a first teaching of the present invention the afore described object is achieved by a generic method, in which

-   -   a selected edge region of the composite sheet metal part is         heated so that the plastic layer arranged between the outer         covering sheets softens,     -   by applying a force to at least one outer covering sheet in the         edge region the covering sheets are pressed against one another         at some points or regions, so that the plastic layer in the edge         region subjected to a force is expelled, and     -   subsequently or at the same time as the application of the force         both covering sheets in the compressed edge region are joined to         one another at least over some regions or points.

In contrast to the method known from the prior art the covering sheets are not bent over and the plastic layer is not removed via abrasive means, but due to the application of a force to at least one outer covering sheet the plastic layer is expelled from the edge region. The edge region of a composite sheet metal part is understood to be a region of the composite sheet metal part that is a distance of 10 mm to 100 mm from the edge of the composite sheet metal part. Due to the joining of the two outer covering sheets over some regions or points in the these edge regions, in which the plastic has been removed, a composite sheet metal part is obtained in a simple manner having a purely metal edge region, which to this extent is therefore also suitable for the conventionally employed joining methods, such as for example fusion welding or soldering. Due to the fact that the bending of the outer covering sheets and the removal of the plastic layer by using abrasive means can be dispensed with, it is found that the production of a composite sheet metal part with a purely metal edge region can be implemented significantly more economically. The method can also be automated extremely easily and as a result provides composite sheet metal parts that can be joined very easily.

Particularly preferably composite sheet metal parts whose plastic layer has a greater wall thickness than the associated metallic covering sheets are joined using the method according to the invention. For example, the metallic covering sheets can have a wall thickness of 0.1 mm to 0.3 mm, whereas the plastic sheet has a wall thickness of 0.35 mm to 0.8 mm. Corresponding composite parts have considerable weight advantages compared to solid materials, and can be joined particularly well using the method according to the invention

According to a first arrangement of the method according to the invention the plastic expelled in the edge region is at least partly removed mechanically and/or via a suction device. A mechanical removal of the displaced plastic can, for example, be performed by abrasion using an abrasive device. The combination of a suction device that sucks out the exiting, soft plastic, and an abrasive device is also conceivable, so that a finishing operation of the outer edge region of the composite sheet metal part after the fabrication of the metal edge region is no longer necessary. The abrasive device can also at the same time be used for further tasks, for example electrode cleaning, for example if roller electrodes are used for heating the edge region or for joining the edge regions.

If the heating of the edge region of the composite sheet metal part is carried out convectively, conductively, inductively, by friction and/or using electromagnetic radiation, a heated shape of the edge region of the composite sheet metal part that matches the intended use can be ensured. With convective warming the heat transfer takes place for example by hot gases via convection. Use is made of the fact that the covering sheets can transfer the heat locally extremely efficiently to the plastic layer arranged between them. In the case of conductive heating the heating zone can be limited locally to strictly defined regions, namely the contact points, through which the current is to flow. In addition, the means for conductive heating can also be used for the application of a force. In those cases in which a contact-free, locally strictly limited heating is desired, this can also take place via induction, i. e., by inducing eddy currents. A further possibility of heating the edge region of the composite sheet metal part from which the plastic layer is to be removed is by friction, for example in which a sonotrode transmits ultrasound vibrations to the composite sheet metal part. This heating of the covering sheets of the composite sheet metal part is also very localised and ensures that the plastic layer in the remaining regions of the composite sheet metal part is not adversely affected. At the same time an ultrasound sonotrode, for example, can be used not only to transmit a force but also to weld the outer covering sheets in the edge region. Finally, the use, for example, of electromagnetic radiation, for example laser radiation in the near infra-red region or also near infra-red (NIR) radiators, provides a particularly convenient and effective heating of specific edge regions of the composite sheet metal part. The use of electromagnetic radiation enables the heating region to be widened or limited in a particularly targeted manner.

According to a further advantageous embodiment of the method according to the invention the application of the force takes place using at least one or more rollers. When using rollers, the contours of edge regions that had previously or simultaneously been heated can be followed by the rollers, and in this way for example longitudinal edges of a composite sheet metal part can be provided in a simple manner with a non-metallic edge region. In this connection it is not important whether one roller is used, which exerts a force on an outer covering sheet, the second outer covering sheet being pressed against a dolly bar or counter holder, or whether two rollers, respectively arranged opposite one another, press against the outer covering sheets. In both cases with conductive heating, for example, the roller can also serve as a contact roller, which is suitable for conducting the current and thus allows a punctiform heating of the edge region.

Preferably, by using one or more rollers the edge region of the composite sheet metal part is welded over some points or regions after or during the application of the force. Owing to the use of the rollers a particularly effective production of a composite sheet metal part with a purely metal edge region is ensured. For example, an arrangement of two pairs of rollers viewed in the longitudinal direction of the edge region can be used to conductively heat the selected edge region first of all via the first pair of rollers and to apply a force, and then using the second pair of rollers to weld the compressed edge region of the composite sheet metal part over some points or regions.

In the edge regions of the composite sheet metal part the overall thickness of the composite sheet metal part is reduced as a result of the plastic that has been expelled. According to a further advantageous arrangement of the method according to the invention, in the compressed edge region of the composite sheet metal part at least some regions on one or both sides are provided to compensate the thickness, so that the overall composite sheet metal part has an almost uniform thickness.

According to a next advantageous variant of the method according to the invention, during the heating and expulsion of the plastic layer between the two outer covering sheets of the composite sheet metal part, a force is exerted on at least one outer covering sheet that is greater than that exerted during the joining of the two covering sheets. In this way the heating temperatures in the edge region to be prepared can be kept low at least during the expulsion of the plastic, so that the damage to the plastic layer that adjoins the metal edge region of the composite sheet metal part is small. In addition, a particularly comprehensive expulsion of the plastic between the two outer covering sheets is thereby achieved, so that the subsequent welding of the two outer covering sheets is accomplished particularly easily. The currents employed in a conductive heating and a subsequent conductive joining can, for example, behave exactly inversely. In the expulsion of the plastic the currents are lower, in order simply to soften the plastic layer. With the joining over at least some regions or points of the outer covering sheets a higher current can be chosen, so as to enable a joint to be produced.

According to a further embodiment of the method according to the invention the composite sheet metal part is joined at the same time, i. e. during the fabrication of the metal edge region, to a further metal part. The fabrication of the metal edge region and the joining to a further metal part can thereby be accomplished in a single process step.

If the composite sheet metal part simply comprises one outer covering sheet of metal and a plastic layer arranged on the covering sheet, the second metal covering sheet can be provided by the metal part to which the composite sheet metal part is to be joined, so that the composite sheet metal part in the edge region can be joined without any problem to the metal part by welding. In this way composite sheet metal parts with an outer covering sheet and a plastic layer arranged thereon can easily become an integral component of appliances or devices, for example dishwashers or railway lines, and their sound-damping properties can be utilised.

According to a second teaching of the present invention the object described above is achieved by a device for carrying out the method, which comprises

-   -   means for positioning a composite sheet metal part,     -   means for warming an edge region of the composite sheet metal         part over some points or regions,     -   means for applying a force by means of a covering sheet of the         composite sheet metal part in the heated edge region, in order         to press this covering sheet against a further metal sheet, so         that the heated and soft plastic layer arranged on the covering         sheet is expelled from the edge region, and     -   means for joining the covering sheet at least over some regions         or points to a further metal sheet in the compressed edge region         of the composite sheet metal part.

The second outer covering sheet of a composite sheet metal part with two outer covering sheets and a plastic layer arranged there between can obviously also be used as a metal sheet. The device enables the method according to the invention to be carried out, so that an economic production of the composite sheet metal parts with two outer covering sheets and a plastic layer arranged there between, and also comprising a metal edge region, is ensured. In addition, the device according to the invention also enables a composite sheet metal outer part with a single outer covering sheet and a plastic layer arranged thereon to be joined economically to a further metal part.

In a simple way longitudinally extending edge regions of a composite sheet metal part can in one arrangement of the device according to the invention be produced with a metal edge region, wherein the arrangement of the device according to the invention is provided with one or more rollers for applying a force and/or for heating and/or for joining the edge region of the composite sheet metal part, as well as with means for effecting a relative movement between the composite sheet metal part and rollers. The relative movement between the composite sheet metal part and rollers enables the contours of an edge region to be followed, and at the same time the application of force, a heating, and simultaneously a welding over some points or regions of the two outer covering sheets of a composite sheet metal part or of the outer covering sheet to a further metal part, becomes possible.

A further arrangement of the device according to the invention enables the edge regions to be machined, for example to remove excess plastic, is not necessary by providing an abrasive device and/or a suction device to remove the expelled plastic. On the one hand, as already explained, a further machining of the composite sheet metal part is avoided, and on the other hand it can be ensured via the suction device, which is preferably arranged in the region of the heating and compression of the edge region, that excess plastic does not interfere with the joining process of the two outer covering sheets or of the outer covering sheet to a further metal part.

In addition, the device according to the invention can furthermore be configured so that a first and a second pair of rollers are provided, wherein the first and the second pair of rollers are arranged behind one another seen in the longitudinal direction of the edge region of the composite sheet metal part, wherein the first pair of rollers is used for the heating and compression of the edge region of the composite sheet metal part and the second pair of rollers is used for the joining over some points or regions of the edge region of the composite sheet metal part. The processing speeds for the production of the composite sheet metal parts with a metal edge region can be increased by allocating the processes of heating and expelling the plastic to the first pair of rollers, and allocating the joining over some points or regions of the edge region to the second pair of rollers.

Finally, if a multi-axis arm robot and/or a handling system is provided according to a further arrangement of the device according to the invention, the automation of the production of composite sheet metal parts with a metal edge region can be significantly enhanced. If, for example, the means for the positioning, the means for the heating over some points or regions of an edge region of the composite sheet metal part, the means for the application of a force to the edge region and the means for the joining of the composite sheet metal part over some points or regions are controlled via a multi-axis arm robot or a handling system, a highly automated fabrication of composite sheet metal parts with a metal edge region can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in more detail hereinafter with the aid of exemplary embodiments and in conjunction with the drawings, in which:

FIGS. 1 and 2 show in a schematic sectional representation a first embodiment of the method for producing a composite sheet metal part with a metal edge region, which employs a roller,

FIG. 3 shows in a schematic sectional view a second embodiment of the method according to the invention, which employs two oppositely facing rollers,

FIGS. 4 and 5 show a third embodiment of the method according to the invention in a schematic sectional view, in which an abrasive and suction device is used,

FIG. 6 shows in a schematic sectional view the implementation of a fourth embodiment of the method according to the invention with pairs of rollers arranged behind one another,

FIG. 7 shows a force/current/time diagram of one embodiment of the method according to the invention,

FIGS. 8 and 9 show in schematic sectional views two further embodiments of the method according to the invention with different methods for heating the edge region of the composite sheet metal part,

FIGS. 10 and 11 show a device for carrying out an embodiment of the method according to the invention with conductive heating of the edge region of the composite sheet metal part,

FIG. 12 shows in a schematic, partially perspective representation, the implementation of the method according to the invention on a flat composite sheet metal part,

FIGS. 13A-13D show in a schematic sectional view four embodiments of a composite sheet metal part with a metal edge region, produced by the method according to the invention,

FIGS. 14A-14B and 15A-15C show the use of a composite sheet metal part produced by the method according to the invention in a dishwasher, and

FIGS. 16A-16B and 17 show in schematic sectional representations the use of a composite sheet metal part produced according to the invention in a railway track.

DETAILED DESCRIPTION OF THE INVENTION

A first embodiment of the method according to the invention is first of all illustrated in FIG. 1 in which a composite sheet metal part 1 consisting of two outer covering sheets 2, 3 and a plastic layer 4 arranged between the covering sheets 2, 3, is heated in its edge region 5 in such a way that the plastic layer 4 in this edge region 5 softens. The heating of the edge region 5 can take place in various ways and means. In the present exemplary embodiment a current is fed to the composite sheet metal part 1 via the roller 6 and the current conducting clamp 7 and via the dolly bar 8, wherein especially in the contact region of the roller 6, namely in the edge region 5, a powerful heating of the upper and optionally of the lower covering sheet 2, 3 takes place so that the plastic layer 4 provided in the edge region 5 appreciably softens. As a result of the force transmitted to the roller 6 in the direction of the composite sheet metal part 1 the upper covering sheet 2 in the edge region 5 is pressed onto the lower covering sheet. At the same time the plastic 4 in the edge region is expelled, so that the edge region 5 becomes purely metallic. This is illustrated in FIG. 2. As can furthermore be seen from FIG. 2, a device 9 is provided for removing the expelled plastic 4. In the case where the two covering sheets 2 and 3 are in contact, the current now flows from the roller 6 via the edge region 5 of the composite sheet metal part to the dolly bar 8 and can thereby heat the covering sheets so that these are welded together, for example. In the compressed edge region both covering sheets are thereby joined to one another at least over some regions or points.

In the figures the thickness relationships of the covering sheets and of the plastic layers are not shown strictly to scale. The wall thickness of the plastic layer is preferably larger than that of the covering sheets. For example, the metal covering sheets can have a wall thickness of 0.1 mm to 0.3 mm, whereas the plastic layer has a wall thickness of 0.35 mm to 0.8 mm. Composite sheet metal parts with covering sheets of 0.25 mm wall thickness and a plastic layer of 0.4 mm wall thickness are particularly preferred. Corresponding composite parts have significant weight advantages compared to solid materials and can be joined particularly efficiently using the method according to the invention.

A similar exemplary embodiment of the method according to the invention is illustrated in FIG. 3 and in FIG. 4. Here two rollers 6 a, 6 b are used in order to exert a force on the edge region 5 which is illustrated by the arrows F. The edge region 5 can as already described hereinbefore be conductively heated by supplying current via the rollers 6 a and 6 b and the current conducting clamp 7. It is, however, also possible to heat the edge region 5 beforehand by other ways and means, so that the plastic layer becomes soft and can then be expelled from the edge region 5 by application of the force F. In FIG. 4 it can be seen that in this embodiment of the method according to the invention two roller-type electrodes 11 a and 11 b are additionally used in order to guide the current flow from one outer covering sheet 2 to the outer covering sheet 3. The roller-type electrodes 11 a and 11 b are connected to one another in an electrically conducting manner. By means of the roller-type electrodes 11 a and 11 b and also by means of the roller-type electrodes 6 a and 6 b it becomes possible for the contours of the edge region of a composite sheet metal part to be followed in the longitudinal direction and in this way the method according to the invention is in each case carried out so that heating can take place continuously. With the aid of the contact and sealing rollers 25 a negative pressure in the housing of the suction device 9 can basically be produced and the abraded plastic can be completely removed from the roller-type electrodes 6 a, 6 b. Furthermore, it is shown in FIG. 4 that, apart from the device 9 for removing the expelled plastic which is illustrated in the form of a suction device, an abrasive device 10 is also provided which is arranged in an abrading manner on the front surface of the composite part. In addition, two contact or sealing rollers 25 are arranged which are mounted in a freely co-rotating manner on the housing of the suction device 9, whereby a negative pressure can be produced in the housing that has a positive effect on the removal of the plastic.

An embodiment of the method according to the invention is now illustrated in FIG. 5 in which the roller-type electrodes 6 a, 6 b are cleaned to remove exiting plastic, so that these can be used satisfactorily for the welding over some regions or points of the edge region 5 of the composite sheet metal part 1. The abrasive device 10 can furthermore also be used to remove expelled plastic at the edge of the composite sheet metal part.

FIG. 6 shows a further embodiment in a schematic sectional view. The two pairs of rollers 6 a, 6 b and 12 a, 12 b are used in order on the one hand to heat and compress the composite sheet metal part 1 in the edge region so that the plastic 4 is expelled from the composite sheet metal part 1 and can be removed by the suction device 9. The composite sheet metal part 1 then passes through the pair of rollers 12 a and 12 b which for the welding over some points or regions are arranged, viewed behind the first pair of rollers 6 a and 6 b, in the processing direction and in the longitudinal direction of the composite sheet metal part. The procedure involving the compression and expulsion of the plastic as well as the welding of the upper and lower covering layers is thereby divided, so that both procedures can be controlled more precisely. Furthermore, owing to this arrangement the processing speed can also be increased. For example, a roller seam can be produced in a simple way in the edge region of the composite sheet metal part at a relatively high rate via the roller electrodes regardless of the expulsion of the plastic in the edge region.

The force/time diagram and current/time diagram illustrated in FIG. 7 describes an embodiment of a method according to the invention with conductive heating and joining of the edge region of the composite sheet metal parts. The production procedure is divided into two sections: in the first section the heating and expulsion of the plastic layer lasting from t0 to t1, and a welding phase lasting from t1 to t2. In the heating and expulsion phase of the method according to the invention a relatively small current I and a relatively high force F are exerted via the rollers on the edge region of the plastic part. The relatively small current in relation to the welding phase allows an adjusted heating of the plastic layer between the two outer covering sheets 2, 3 so that on account of the great force this plastic layer can be expelled from the gap between the two outer covering sheets in the edge region 5 until the two covering sheets 2, 3 contact one another at time t1 and there is virtually no longer any plastic between them. The welding phase lasting from t1 to t2 can then start, in which the force F can be reduced, though the current I is increased further so that the metal covering sheets weld to one another.

FIG. 8 shows a further exemplary embodiment of the method according to the invention, in which the edge region of the composite sheet metal part is heated and compressed by friction, in particular using ultrasound sonotrodes 13 a and 13 b. In addition, the suction device 9 is again shown in FIG. 8. A further possibility of heating the edge region is shown schematically in FIG. 9. In FIG. 9 means 14 a, 14 b are provided for the inductive heating and a pair of rollers 15 a, 15 b is arranged behind them with the aid of which the soft plastic is expelled so that the two outer covering sheets of the composite sheet metal part 1 can then be welded to one another. Instead of the means for the inductive heating 14 a and 14 b there can furthermore obviously be used means for heating the edge region using electromagnetic radiation for example laser radiation or near infra-red radiation which also lead to an effective, contact-free heating of the edge region of the composite sheet metal part.

Resistance welding of the edge region of the composite sheet metal part is preferred, however. FIG. 10 shows the current conduction paths that are necessary for this purpose. Thus, on the one hand, a current bridge 16 is provided between the roller-type electrodes 11 a and 11 b. In addition, the roller-type electrodes are connected to one another via a further current bridge 17 in which the current is conducted via sliding contacts, as illustrated on an enlarged scale in FIG. 11, through the roller-type electrodes 6 a and 6 b to the current bridge 17. The power source 18 is connected via the roller axes of the roller-type electrodes 6 a and 6 b. FIG. 12 now shows schematically one view of the production of the composite sheet metal part with a metal edge region. In the process step A the starting point is a composite sheet metal part 1 comprising two outer covering sheets 2, 3 and a plastic layer 4 arranged between the covering sheets. The flat composite sheet metal part or composite sheet thereby produced is passed in the process step B to a handling system 19. The handling system 19 a has a device 19 b according to the invention for producing a composite sheet metal part with a metal edge region. Alternatively, the device 19 b can also be arranged on a multi-axis arm robot 19. The multi-axis arm robot 19 or the handling system 19 a now follows the contours of the edge regions 5 of the composite sheet metal part 1 and produces a purely metallic edge region there. The edge regions have a width of approximately 10 to 100 mm. Alternatively, the composite sheet metal part 1 can also first of all undergo a forming process and then be fed in the formed state as process step B′ to the handling system 19 a, which then moves round the edge region 5 of the composite sheet metal part 1 a and thus produces a purely metallic edge region 5. In the process step C the thus produced composite sheet metal part 1 which is flat or possibly pre-formed with a metal edge region can be passed to a further forming step or processing step. The section C′ now shows on an enlarged scale once again the edge region 5 of the composite sheet metal part 1. The purely metallic edge region 5 comprising no plastic layer can clearly be recognised. After the forming to produce the specific composite sheet metal part in the process step D the said composite sheet metal part can be joined to further sheet parts as illustrated in the process step E via a seam formation 20 or by welding to a further structural part as illustrated in E′. The composite sheet metal part with a metal edge produced according to the invention can, as illustrated in E and E′, be joined in a simple manner to further structural parts by using conventional joining techniques.

FIGS. 13 a), b), c) and d) show in a schematic sectional view the edge regions 5 of composite sheet metal parts 1 that have been produced with exemplary embodiments of methods according to the invention. In FIG. 13A both outer covering sheets 2, 3 are pressed against one another, so that the composite sheet metal part 1 tapers on both sides in the edge region 5. In FIG. 13B on the other hand only the upper covering sheet 2 has been deformed so that a thickness compensation, as illustrated in FIG. 13D, is achieved by unilateral arrangement of a further sheet 2 a. FIG. 13 c shows the thickness compensation in the case of an edge region 5 tapering on both sides of a composite sheet metal part 1. Here both sides are to be covered with sheets 2 a and 3 a. Common to all four illustrated exemplary embodiments is that they comprise a welding 5 a in the edge region, which joins the sheets 2 a, 3 a provided in the edge region 5 or covering sheets 2, 3 of the composite sheet metal part to one another.

Further application possibilities of the method according to the invention are illustrated in FIGS. 14A and 14B and also 15A, 15B, and 15C. In FIG. 14A a composite sheet metal part 1′ comprising an outer covering sheet 2′ and a plastic layer 4′ is joined to a stainless steel sheet 22 of a dishwasher. In this connection the edge region of the composite sheet metal part 1″ is heated by a roller-type electrode 6 a, the plastic layer 4′ is expelled and the edge region is then welded to the stainless steel sheet 22. FIG. 14B shows the finished produced composite sheet metal part 1′ installed on a dishwasher 23. The method is illustrated in its individual steps once again in FIG. 15A and 15B as well as 15C. First of all a contact electrode 6 a is positioned in the edge region of the composite sheet metal part 1′ as illustrated in FIG. 15A and the plastic in the edge region 5 is heated and removed from the gap between the sheets 2′ and 22. Then in a second process step using a resistance welding procedure the outer covering sheet 2′ is welded to the stainless steel sheet 22. In this case an additional roller-type welding electrode is used so that the steps 15A and 15B can follow one another in succession. The finished produced composite sheet metal part 1′ is then fastened to a dishwasher 23. The composite sheet metal parts 1′ lead to a significant sound-damping effect and can be fastened in a simple manner using the method according to the invention, for example to a dishwasher.

Finally, FIGS. 16A, 16B, and 17 show a further use of a composite sheet metal part 1 with a metal edge region 5 produced according to the invention. The composite sheet metal part 1′ comprises, as in FIGS. 14 and 15, simply one outer covering sheet 2′ and a plastic layer 4′. In the first process step the plastic layer 4′ in the edge region 5 of the composite sheet metal part 1′ is heated via a roller-type electrode 6 a and expelled from the gap between the outer covering sheet 2′ and the rail 24, which in this case forms the metal part. The outer covering sheet is then welded to the rail 24 using a welding electrode 25 which can also be formed as a roller-type electrode. FIG. 17 shows a sectional view of the sound-damped rail 24, which respectively comprises two composite sheet metal parts 1′ on both sides. As is evident from the applications discussed hereinbefore, a composite sheet metal part 1′ with an outer covering sheet 2′ and a plastic layer 4′ arranged thereon can be joined in a simple manner by the method according to the invention to a further metal part, for example to the rear wall of a dishwasher 22 or a rail 24. The method according to the invention in this way significantly broadens the possible applications of composite sheet metal parts. 

1. Method for producing a composite sheet metal part with a metal edge region, which comprises two outer covering sheets of metal and at least one layer arranged between the covering sheets consisting of a plastic, the method comprising the steps of: heating a selected edge region of the composite sheet metal part in such a way that the plastic layer arranged between the outer covering sheets softens, applying a force to at least one outer covering sheet in the edge region such that the covering sheets are pressed against one another at some points or regions so that the plastic layer in the edge region subjected to a force is expelled, and joining, subsequently or at the same time as the application of the force, both covering sheets in the compressed edge region to one another at least over some regions or points.
 2. Method according to claim 1, wherein the plastic expelled in the edge region is at least partially removed mechanically and/or by means of a suction device.
 3. Method according to claim 1, wherein the heating of the edge region of the composite sheet metal part takes place by at least one of convectively, conductively, inductively, by friction or by using electromagnetic radiation.
 4. Method according to claim 1, wherein the application of the force takes place using at least one or more rollers.
 5. Method according to claim 1, wherein the edge region is welded over some points or regions using one or more rollers.
 6. Method according to claim 1, wherein the compressed edge region of the composite sheet metal part sheets for thickness compensation are arranged at least over some regions on one or both sides.
 7. Method according to claim 1, wherein the force exerted during the heating and expulsion of the plastic layer is greater than during the joining of the two covering sheets.
 8. Method according to claim 1, wherein the composite sheet metal part is joined at the same time to a further metal part.
 9. Method according to claim 8, wherein the composite sheet metal part comprises only one outer covering sheet of metal and a plastic layer arranged on the covering sheet, and a second metal covering sheet is provided by the metal part to which the composite sheet metal part is to be joined.
 10. Device for carrying out a method according to claim 1 comprising: means for positioning a composite sheet metal part, means for warming an edge region of the composite sheet metal part over some points or regions of an edge region of the composite sheet metal part, means for applying a force by means of at least one covering sheet of the composite sheet metal part in the heated edge region in order to press this covering sheet against a further metal sheet so that the heated and soft plastic layer arranged on the covering sheet is expelled from the edge region, and means for joining the covering sheet at least over some regions or points to the metal sheet in the compressed edge region of the composite sheet metal part.
 11. Device according to claim 10, wherein there are provided one or more rollers for applying a force and/or for heating and/or for joining the edge region of the composite sheet metal part and also means for effecting a relative movement between the composite sheet metal part and rollers.
 12. Device according to claim 10, wherein an abrasive device and/or a suction device is provided to remove the expelled plastic.
 13. Device according to claim 10, wherein a first and a second pair of rollers are provided wherein the first and the second pair of rollers are arranged behind one another viewed in the longitudinal direction of the edge region of the composite sheet metal part, wherein the first pair of rollers is used for heating and compressing the edge region of the composite sheet metal part and the second pair of rollers is used for joining, over some points or regions, the edge region of the composite sheet metal part.
 14. Device according to claim 10 wherein a multi-axis arm robot and/or a handling system is/are provided. 